1. Field of the Invention
This invention relates to a thin film magnetic head and a method for manufacturing the same usable for a magnetic recording and reading device such as a magnetic disk device.
2. Related Art Statement
For realizing a high density recording in a magnetic disk device, a recording track width to be wrote by a thin film magnetic head has become extremely narrower to, for example, not more than 1.0 xcexcm. A width of a pole part in the thin film magnetic head is required to be narrower for obtaining such an extremely narrow track-width, and as its means, it is known that an air bearing surface (hereinafter, abbreviated to xe2x80x9cABSxe2x80x9d) of a slider opposite to a magnetic recording medium is processed. In the case of such a technique to obtain the extremely narrow track-width, the surface of the slider opposite to the magnetic recording medium is polish-processed, etc., to form a gap having a given depth, and thereafter the area containing the magnetic film constituting the pole part is dug up to form a trim structure. Or a pattern is formed on the ABS by a photolithography technique and the ABS is processed along the formed pattern by ion-milling, etc. For example, [IEEE Transactions on Magnetics], Vol. 27, No. 6, November 1991 discloses the technique that a width of a pole part exposed to an ABS is reduced by converging ion beam. Moreover, [IEEE Transactions on Magnetics], Vol. 30, No. 6, November 1994 discloses the technique that a width of a pole part to define a track width is reduced.
One of the problems in the above conventional techniques is not suitable for mass-production since a complete thin film magnetic head is processed. The other problem is that in employing the above processing method, for protecting, from oxidization and erosion, the end of the magnetic film constituting the pole part exposed to the bottom face of the thus dug depressed portion, a protective film is required to be formed on the whole surface opposite to the recording medium containing the ABS and the depressed portion. The protective film is generally made of diamond-like carbon (hereinafter, abbreviated to xe2x80x9cDLCxe2x80x9d). As the thickness of the protective film is increased, the amount of the material to be stuck to the ABS of which the protective film is made is obviously increased, so that spacing loss is rose up and thereby electromagnetic conversion characteristics are degraded.
The above problems is not only peculiar to the digging process to narrow the track width, but also is brought about to the case of digging up the area containing the pole part.
It is an object of the present invention to provide a thin film magnetic head having a narrowed recording track-width.
It is another object of the present invention to provide a thin film magnetic head having an excellent overwrite characteristic
It is still another object of the present invention to provide a thin film magnetic head capable of reducing its spacing loss.
It is further object of the present invention to provide a thin film magnetic head capable of protecting a magnetic film constituting a pole part from oxidization and erosion, etc.
The present invention also relates to a method for manufacturing a thin film magnetic head and its object is to provide the manufacturing method suitable for manufacturing the above thin film magnetic head.
A thin film magnetic head according to the present invention comprising:
a slider having an air bearing surface opposite to a magnetic recording medium,
an inductive type thin film magnetic head including a first magnetic film having a first pole part of which the forefront surface is exposed to the air bearing surface and a first yoke part extending to the opposite side of the air bearing surface from the first pole part, a second magnetic film having a second pole part opposite to the first pole part of the first magnetic film via a gap film and extending to the opposite side of the air bearing surface from the second pole part to be connected to the first yoke part of the first magnetic film, a thin film coil wound so as to be capable of passing through the magnetic circuit surrounded by the first and the second magnetic films and. supported by an insulated film, and a protective film to cover the first and second magnetic films, the gap film and the thin film coil, the inductive type thin film magnetic head being supported by the slider and constituting an inductive type thin film magnetic head element, wherein:
the forefront surface in the air bearing surface side of the second yoke part of the second magnetic film is receded from the air bearing surface and the second pole part has a first step d1 in the running direction of magnetic recording medium and a second step d2 in the perpendicular direction to the running direction, and the protective film embeds the first and the second steps between the periphery of the forefront surface of the yoke forefront surface and the second pole part.
In the thin film magnetic head according to the present invention, the forefront face, the boundary between the second yoke part and the second pole part is receded from the ABS, and the second pole part having steps to the periphery of the ABS is elongated to the ABS from the forefront face of the yoke. Thus, the magnetic flux generated from the thin film coil flows to the second pole part from the second yoke part and thereby is efficiently conducted to the forefront face of the second pole part, resulting in the development of the overwrite characteristic.
Moreover, since the inductive type thin film magnetic head element is entirely covered with the protective film, it can be protected with the protective film. The protective film covers the thin film magnetic head, and besides, it embeds the steps between the periphery of the yoke forefront surface and the second pole part. In the second pole part, the forefront surface of the first and the second pole parts, which is needed for magnetic conversion, are to be exposed to the outside and the side, etc. of the second pole part is covered with the protective film. Thus, the magnetic film constituting the second pole part can be protected from oxidation and erosion.
Moreover, since the side, etc. of the second pole part is covered with the protective film indispensable to protect the inductive type thin film magnetic head element, a protective film made of DLC, etc. may be formed in a minimum thickness. Thus, the increase of the spacing loss due to the protective film can avoided and its electromagnetic conversion characteristics can be improved.
The thin film magnetic head according to the present invention can have the second pole part having a width of not more than 1 xcexcm. In this case, it is preferable, for balancing each part of the magnetic head and obtaining good characteristics, that the yoke forefront surface of the second yoke part is receded from the ABS by 0.1-1.5 xcexcm and the first and second steps d1 and d2 are 0.1-4 xcexcm and 0.1-5 xcexcm, respectively.
Moreover, in the preferred embodiment of the thin film magnetic head according to the present invention, the second magnetic film includes a main magnetic film and a subsidiary magnetic film, the main magnetic film being opposite to the insulated film to form the second pole part and being extended backward to the ABS to be connected to the first magnetic film, the subsidiary magnetic film being formed-in the opposite side to the opposing surface of the main magnetic film to the insulated film to constitute the yoke forefront surface.
Moreover, in the thin film magnetic head according to the present invention, the gap film is formed so as to cover the first magnetic film almost entirely and the insulated film is provided on the gap film. The yoke forefront surface may rise up on the gap film in the forefront of the insulated film in the ABS side or in the position near the ABS from the forefront of the insulated film. Particularly, the latter structure is effective for reducing a dimension of Throat Height.
Furthermore, it is preferable to remove the gap film and the part of the first magnetic film in its thickness around the one side or the both sides of the first pole part, thereby to form a depressed portion to define the width of the first pole part. In the case of forming depressed portions in the both sides of the first pole part, the first pole part can have a width almost equal to that of the second pole part as they are viewed from the ABS.
Moreover, the thin film magnetic head according to the present invention preferably has a laminated magneto resistive effective element besides the inductive type thin film magnetic head element.
This invention is also relates to a method for manufacturing a thin film magnetic head in which a first magnetic film, a gap film and a thin film coil supported by an insulated film are formed on a substrate to be a slider and thereafter a second magnetic film is formed, the step of forming the second magnetic film comprising the steps of:
forming a main magnetic film having a pole part opposite to the first magnetic film via the gap film and a yoke part connected to the first magnetic film backward in the opposite side of the pole part,
forming a pattern of resist around the main magnetic film so as to cover the pole part of the main magnetic film and leave a space between itself and the sides of the pole part in the area within the yoke part from the pole part, and
forming a subsidiary magnetic film in the area surrounded by the resist pattern.
In the present invention, the step of forming the subsidiary magnetic film within the area surrounded by the resist pattern may be performed by a electroplating method or a sputtering method.
Moreover, in the preferred embodiment of the manufacturing method of the thin film magnetic head according to the present invention, the gap film and the first magnetic film are partially removed in the both sides in its width direction of the pole part before or after the subsidiary magnetic film is formed, to form depressed portions. In the former case, it is preferable to stick a non-magnetic film at least on the exposed surface, formed by the above removing, of the first magnetic film before forming the subsidiary magnetic film.